The invention concerns an agitator [stirrer element] for cylindrical containers filled with paint or the like, especially for touch-up sticks to repair paint damage on automobiles, this agitator being constructed as a tubular hollow member guided in the container in the axial direction of the latter, surrounding a brush attached to a cap, and exhibiting radially outwardly projecting ribs.
Agitators are known (German Patent No. 1,161,795) which are fashioned as a coiled wire section in the manner of a spiral-shaped compression spring. Such agitators have the disadvantage that they must be normally manufactured from spring steel and permit intensive intermixing only with repeated shaking of the container, due to their configuration. The design must in each case furthermore be such that a certain tumbling motion of the spiral spring section is made possible, because otherwise no appreciable intermixing can occur in the zones between the outside periphery and the inside diameter of the container or in the inside of the spiral spring section. Therefore, it is also necessary to observe the maintenance of tolerances regarding the outside diameter and the length of the wire section, if a jamming of the agitator is to be safely avoided.
Furthermore, known are agitators of the type mentioned hereinabove (DOS-German Unexamined Laid-Open Application 2,127,748), wherein perforated disks or cruciform parts are offset with respect to each other in the axial direction and surround a tubular inner part. However, such an arrangement has the disadvantage that the resistance of the shaker element against axial movement is likewise increased by the surface area of the disks, and that relatively large contact areas are produced between the lowermost disk and the container bottom, where the element can stick to the pigments of the paint. Detachment in such a case is possible only with great difficulties, or not at all.
Therefore, the invention has an object of constructing an agitator of the type mentioned above in such a way that intensive intermixing occurs in all zones of the container, even if the container is only slightly shaken to move the agitator.
The invention resides in that ribs are fashioned in the manner of vanes of a fan wheel and are uniformly distributed along the periphery of a hollow element, which latter element is constructed a a cylindrical tube, wherein the outer edges of the ribs are located on an imaginary cylinder, the diameter of which is smaller than the inner diameter of the container. This construction permits a simple manufacture of the agitator, for example as an injection-molded or die-cast part of plastic or of metal. Due to the ribs operating in the manner of propellers, the construction ensures excellent intermixing, even with minor shaking. In this connection, it is very advantageous to arrange the outer edges of the ribs on an imaginary cylinder, the diameter of which is slightly smaller than the inner diameter of the container, because thereby also the marginal zones of the liquid provided in the container can already be affected with a single upward and downward motion of the agitator and are not initially intermixed by repeated tumbling motions of an agitator.
It is also advantageous that the area coming into contact with the bottom of the paint-filled container, corresponding essentially only to the end faces of the ribs, can be kept at a very small size. Therefore, sticking of the agitator need not be feared even when the unit is unused for a relatively long period of time.
These non-stick properties can be still further improved by selecting the axial length of the enveloping cylinder for the outer edges of the vanes to be larger than the length of the tube, and by extending the leading edges of the vanes at an angle to the longitudinal axis inwardly. By this construction, there result only spot-like contact points in the outermost region of the vanes, so that the contact areas with the bottom of the container of the touch-up stick are reduced to a minimum. The novel design therefore secures in any event the free movability of the agitator within the paint container.
It is also advantageous if, in such an arrangement, for reasons of manufacturing technology, the fan blades proper are fashioned as straight blade vanes oriented merely at an angle with respect to the axial extension of the agitator. Such an agitator can be produced in a very simple way, for example by the die-casting method, from a metal.
It has proved to be sufficient and advantageous, according to a preferred embodiment, to provide four blade-like ribs, the two leading sides of which are oriented at right angles to the tube wall and are offset with respect to each other in the peripheral direction. In this embodiment, flow channels can form between the blade-like ribs; if the length of the agitator is approximately designed so that it corresponds to one-half the length available in the container for the axial movement of the agitator, these flow channels then effect, with a one-time shaking step, already a sufficient turning of the agitator, translated into the desired mixing motion of the liquid. This novel construction of the agitator thus permits a secure, perfect guidance of the agitator in the container, a simple manufacture, and an excellent mixing effect, without the brush provided in the container being subjected to damage by or contact with the moving agitator.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings, which show, for purposes of illustration only, plural embodiments in accordance with the present invention.